There is a risk in aircraft fuel systems of a build up of static electricity on one component in comparison to another component to which it is connected. In the prior art, a so-called bonding lead is connected to each side of the joint in order to electrically connect the components and prevent static build up. An example of such a bonding lead is described in the prior art section of US2008/0078880.
Bonding leads are traditionally made of highly conductive materials in different forms. These satisfy equipotential and electrostatic discharge requirements but allow the flow of lightning current across the joint. There is a risk that a break in such a bonding lead can result in intermittent contact and a source of sparking should high levels of electricity flow in the lead, for instance during a lightning strike.
An example of this problem is shown in FIGS. 14 and 15. A bonding lead 62 couples a pair of fuel pipes 60, 61 across a joint between the pipes. The pipes are fitted within a fuel tank, close to a fuel tank wall 63. If the lead 62 breaks, the resulting two parts 62a, 62b will hang down as shown in FIG. 15 and there is a risk that one of the parts (in this case 62b) will make intermittent contact with the fuel tank wall 63.
The present invention seeks to reduce this risk but continue to ensure that static charge cannot build to nuisance or dangerous levels.